You can sell them anywhere
No they do not
You can sell them on eBay
ya you can
toywiz.com
eBay
yes, they do.
you cant sell any yu-gi-oh cards for a full price unless it is in PERFECT condition. but if it is a rare card you are going to sell you can sell it on eBay for a good price.
www.Ebay.com www.criglist.com and Amazon
vaskolius.wordpress.com
Depends where you live.
Yes , but they may not sell or fetch as much as new cards that are been sold.